The present invention relates to a heated mirror. More specifically, the present invention relates to a mirror including resistive layer and pair of spaced electrodes for providing current to the resistive layer.
Outside rear mirrors of vehicles can be affected by weather, and become clouded with water droplets, frost and ice, particularly in the winter months. The affect is to degrade the rearward viewing and, in turn, lowering driving safety. It is not uncommon for drivers to resort to the use of mechanical things, such as scrapers, towels, or the like to remove the frost and/or ice from the mirror until enough of the reflective surface of the mirror has been cleared.
In order to overcome this problem, heated mirrors have been introduced in the past. Conventional heated mirrors include a glass plate defining a suitable geometric shape for the mirror. A reflective layer is applied either at the front or rear part of the reflective layer. A resistive element is, in turn, fixed to the reflective layer by means of an adhesive film.
The resistive element usually consists of a coil formed by an electric conductor which is applied to the rear of the reflective surface and has, at its ends, terminals for connection to an electric power source. Heat is then generated to the Joule effect. However, the heat generation is not perfectly uniform and the mirror is heated by means of a transmission of the heat by conduction from the resistive element that generated it, through the reflective surface in the glass layer to the external surface to be demisted, defrosted or deiced. Accordingly, it is necessary to supply adequate electrical power to the resistive element for a certain time in order to produce the gradual heating of the entire volume of glass.
Other attempts for heating mirrors include providing a glass body which has a film of an electrically conductive metal disposed on one surface (a first surface or second surface) which also provides a reflective surface (on the first surface). Two conductive electrodes are associated with the film to induce an electric current in the film to therefore heat the conductive material to produce enough energy to demist, defog, or deice the mirror assembly. Such a mirror is shown, for example, in PCT Published Application WO 99/62303 published Dec. 2, 1999 (Feb. 12, 1999).
Similarly, a heated mirror including a resistive film having a pair of electrodes is shown in U.S. Pat. No. 5,990,449 to Sugiyama, et al.
According to one aspect of the present invention, there is provided a mirror assembly comprising a substrate including a contact surface. A resistive heating layer is disposed on the contact surface of the substrate. A plurality of spaced electrodes are attached to the resistive heating layer. The spaced electrodes are adapted to induce a current on the resistive layer between the electrodes. The substrate is polished in the direction of current flow between the electrodes.
According to another aspect of the present invention, there is provided a mirror assembly comprising a plastic body defining front and rear surfaces. A resistive heating layer is disposed on the rear surface of the plastic body. A reflective surface is disposed on the front surface of the plastic body. A plurality of spaced electrodes are secured to the heating layer. The spaced electrodes are adapted to induce a current in the heating layer between the electrodes.
According to another aspect of the present invention, there is provided a mirror assembly comprising a plastic body defining front and rear surfaces. The resistive heating layer is disposed on the front surface of the plastic body. A reflective surface is disposed on the heating layer. A plurality of spaced electrodes are secured to the heating layer. The spaced electrodes are adapted to induce a current on the heating layer between the electrodes.
According to yet another aspect of the present invention, there is provided a method of constructing a mirror comprising the steps of obtaining a substrate having front and rear surfaces. A contact surface of the substrate is polished in the direction of current flow. A resistive layer is deposited on the rear surface of the substrate. A plurality of spaced electrodes are attached to the heating layer. The spaced electrodes are adapted to induce a current on the heating layer between the electrodes in the direction of the polishing of the contact surface.